Pests and diseases of
berries in the home garden.
Bruce Bordelon, Professor, Department of Horticulture and
Strawberries are among the most popular fruit to grow in the
home garden. They take up little space, produce fruit one year after planting,
and provide a generous supply of tasty berries for a month or more (Picture 1).
Red raspberries are another popular home fruit. While they take a bit more
space, they are easy to grow and provide plenty of fruit throughout the summer, and into
fall if you have primocane fruiting types (Picture 2). However, anyone who has
tried to grow fruit at home knows that it is difficult to produce berries that are
as perfect as we find in the grocery store. Some of the most common problems of
locally grown berries are damaging pests and diseases. Of particular concern
during harvest are slugs, sap beetles, and Botrytis gray mold.
Botrytis gray mold is a diseased caused by the fungal
pathogen Botrytis cinerea. Botrytis
is a common saprophyte and pathogen of a number of fruit and ornamental crops.
In strawberries and raspberries, the fungus invades during bloom and usually
infects the dying petals or stamens. The fungus remains latent until the fruit
begins to ripen then progresses into the ripening berry to cause a rot. In
strawberries, you often find infections starting at the top of the berry near
the cap, where the dying flower parts remain (Picture 3). In raspberries, the
disease can be particular serious following a few days of rain, especially on
fall bearing types. (Picture 4)
Sap beetles (Stelidota
geminata), are a common pest, especially of strawberries. The adult beetles
invade the plantings as the fruit ripens and feed on berries, leaving deep
cavities and tunnels. This damage often leads to development of secondary rots
(Picture 5). The adult beetles are small, about 1/8 inch long, oval, and mottled
brown in color (Picture 6). They are difficult to see because they usually drop
to ground when disturbed. Growers are often surprised by the size of the
cavities considering the small size of the beetles. We often hear complaints of
bird pecking, but I suspect most of the damage we see is from sap beetles, not
Picnic beetles (Glischrochilus
species) are another potential pest of berries. They are more common on
raspberries, but are opportunists and can be found feeding on strawberries as
well. The adults are larger than sap beetles, about ¼ inch long, dark in color,
usually with four orange spots on the back. One distinguishing characteristic
is that they have knobbed antennae (Picture 7). They are quite common on red
and yellow raspberries (Pictures 8 and 9).
species) are molluscs, not insects. But they cause damage to strawberries that
resembles damage from sap beetles. They chew deep holes in the surface of the
berries, especially under the cap. Those found is strawberries are usually
small, less than one inch long, though certain specimens can be much larger.
Control: Sanitation is the key to managing pests and
diseases in the home strawberry planting. Since beetles are attracted to
overripe fruit, pick often and discard all damaged fruit away from the
planting. Keep berries from direct contact with soil by maintaining a layer of
straw mulch. One complication is that mulch also provides an ideal habitat for
sap and picnic beetles and slugs. One way to help is to keep the strawberry rows
narrow with some bare between. This will allow the surface to dry. Use of
insecticides for sap beetles and slugs is not recommended due to the frequent
harvests. Bait buckets containing overripe fruit and a bit of soapy water can
be very effective at trapping beetles. For Botrytis, if fungicides are
considered, they should be applied during bloom when infections are likely to
occur. Application near harvest is not effective at controlling the disease.
Sanitation and vigor management is helpful for raspberries.
Keep the rows relatively narrow at the base, control weeds to provide an open
canopy environment, and do not apply more fertilizer than the plants need. As
with strawberries, for Botrytis control, any applications of fungicide should
be during bloom.
More information about strawberry pests can be found in
ID-146 Managing Pests in the Home Fruit Planting. https://mdc.itap.purdue.edu/item.asp?item_number=ID-146-W